Carburetor throttle control



1944- l. E COFFEY 2,340,736

CARBURETOR THROTTLE CONTROL Filed Feb. 8, 1941 2 Sheets-Sheet 1 INVE NTOR v 4" 6 m5 (3- IRVEN E. COFFEY FIG.2.

ATTORNEY Feb. 1, 1944. E. COFFEY CARBURETOR THROTTLE CONTROL 2 Sheets-Sheet 2 Filed Feb. 8, 1941 FIGQ4.

I INVENTQR IRVEN E. COFFEY ATTORNEY Patented Feb. 1, 1944 CARBURETOR THROTTLE CONTROL Irven E. Cofley, Normandy, M0,, asslgnor to Car- 7 ter Carburetor Corporation, St. Louis, Mo a corporation of Delaware Application February 8, 1941, Serial No. 378.031

5 Claims.

This invention relates to carburetors for internal combustion engines and consists partic-- ularly in novel means for limiting the throttle opening movement for cold starting of the ensine and for rendering the means inoperative after the engine is started.

In starting an automobile engine, particularly when cold, it is dificult, or impossible, for the driver to open the carburetor throttle valve to the most advantageous position since the usual accelerator pedal or button and connecting linkage ls not designed to give any exact indication.

as to the position of the throttle valve at any moment during the movement thereof. In cases where the engine starter is energized coincident with opening movement of the throttle, the moment when the starter switch is closed may not correspond with the proper positioning of the throttle valve for cranking and, furthermore, there is usually provision for continued opening movement of the throttle after the switch is energized without sensible difference in the feel" of the throttle pedal. Excessive opening of the throttle valve during cranking may delay or prevent starting and, in addition, may cause an excessive discharge from the accelerating pump and consequent "loading of the engine intake system.

In each of co-pending applications, Serial 293,297, filed September 2, 1939, by the present inventor and Serial No. 347,879, filed July 27th, 1940 in the name of Harold A. Carlson, now Patent Serial No. 2,307,486 issued Jan 5, 1943, there is disclosed an automotive carburetor having a thermostatic choke valve and throttle control mechanism. designed to operate a starter switch, together with means to sensibly indicate to the driver that the throttle valve is open far enough to close the starter switch. Such indication also serves to prevent the driver from inadvertently opening the throttle far enough to partially open the choke valve against the thermostat, a feature commonly provided in automatic choke carburetors to permit unloading. However, with this arrangement, as well as in prior art carburetors with which applicant is familiar, there is no way to insure setting the throttle valve in an exact predetermined position during starting.

Accordingly, an object of the present invention is to provide means for definitely fixing the position of the throttle valve during cranking of a cold engine, without requiring limitation of the movement of the throttle control pedal or button.

A more detailed object isto provide combination throttle valve and starter switch actuating mechanism arranged to insure predetermined positioning of the valve and switch contacts without limiting the movement of the throttle pedal or button.

Still another object is to provide throttle valve actuating mechanismadapted to limit the opening movement of the throttle valve to a desired predetermined position and so as to close the starter switch for cold starting and, in addition,

upon continued depression ofthe accelerator pedal, to cause opening of the choke and further opening of the throttle for unloading.

Still another object is to provide means for preventing "loading of the engine intake system due to excessive discharge from the accelerating pump during cranking.

These objects and other more detailed objects hereafter appearing are attained substantially by the structure illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevation of a carburetor embodying the invention. a portion containing the pump structure being broken away.

Fig. 2 is a partial side elevation of the carburetor illustrating the linkage moved to a point just before unloading.

Fig.3 is a section taken substantially on line 3-3 in Fig. 1.

Fig. 4 is a section taken substantially on line 4-4 in Fig. 3.

The carburetor in Fig. 1 includes a barrel l forming a. down-draft mixture conduit and provided with an unbalanced choke or starting valve 2 on a shaft 3 journaled in the upper part of the mixture conduit wall, and a butterfly throttle valve I mounted on a shaft 5 journalled in the lower part of the mixture conduit wall. A housing 6a mounted adjacent the choke valve 2 encloses suitable automatic choke mechanism, such, for instance, as disclosed and claimed in Coffey Patent #2,085,351, for yieldingly closing the choke valve during cold starting.

A plate element 6 is rigidly secured to one end of throttle shaft 5 and has an extension 1 for contacting a stop 20 (to be described) to position the throttle valve for cold engine starting. Plate 6 is also provided with inwardly projecting lips 8 threadedly receiving adjustment screw 9 for engaging a rib l0 projecting from the carburetor barrel for establishing the normal idling position of the throttle valve when the engine is warm. The intermediate portion of the plate 6 is provided on one side with inwardly projecting lips ll threadedly receiving a fast idle screw 12.

Rotatably mounted on a pintle l3 adjacent the throttle valve is a cam element It which is connected to the choke for movement therewith by an arm 15, link 13, and a second arm I! rigid with the choke shaft 3.

When the choke is closed, cam element II is positioned so that the high portion l3 thereof will be engaged by fast-idle screw l2 to limit the closing movement or the throttle valve to a fastidle position. When the choke valve is fully open, a recessed portion is is opposite screw l2 to permit the previously mentioned screw 3 carried by the plate element 6 to engage the rib It to position the throttle for normal idling. Cam element I4 is also provided with a finger 20, forming a stop for cooperating with plate extension I,

A bell crank 25, rotatably mounted on the throttle shaft 5 between arm 6 and the carburetor barrel, is provided with an apertured arm 26 for connection to the usual accelerator pedal and a second arm 21 having an apertured lug 28 for receiving one end of a tension spring 29.

The other end of the tension spring is secured to one of the inwardly projecting lips 8 of plate element 6. The intermediate portion of crank is provided with an outwardly projecting finger 30 for contacting the underside of plate extension 1 when the crank 25 is rotated counterclockwise, as seen in Fig. 1, to close the throttle.

A sleeve rigid with crank 25 closely surrounds throttle shaft 5 and is journalled in a portion of the carburetor body, as illustrated in Fig. 3. Sleeve 35 is provided with a milled groove 36, illustrated in Figs. 3 and 4, forming a cam surface 31 for contacting a ball 38. Under certain conditions, ball 38 constitutes an operative connection between sleeeve 35 and a plunger 39 forming part of a starter switch device 40, as described and claimed in Cofiey Patent #2,174,313. When the ball is seated in groove 38, as shown, clockwise rotation of crank 25 and sleeve 35 moves plunger 39 outwardly against spring 48 and causes switch fingers 46 to contact terminals 41, closing the switch. When the choke valve is closed, such closing of the starter switch occurs just prior to engagement of cam finger 20 by extension 1 on plate 6.

Rigidly secured to the end of throttle shaft 5 opposite crank 25 and at plate 6, is an arm ii connected 'to a lever 42 by means of a link 33. Lever 42 is pivoted on shaft 44 and is connected to accelerator pump piston 45 by a link 45a so that the piston will be depressed as the throttle valve is opened.

The operation of the mechanism is as follows:

During clockwise movement of manual control crank 25 by the accelerator pedal from normal idling position, with screw 9 engaging rib Hi, to the position shown in Fig. l, crank 25and plate element 6 move as a unit with the throttle valve. Assuming that the choke valve is closed by the thermostat in housing 6a, cam element M will be so positioned that the end of finger 23 thereon is engaged by the end of extension I on the plate element, stopp ng the rotation of the plate element and the throttle valve. When so stopped, switch is closed, as described above, and the valve is in the predetermined best starting position. Thereafter, continued depression of the accelerator pedal and rotation of crank 25, tensions coil spring 29, as in Fig. 2. Upon still further opening movement'of crank 25, arm 21 thereof engages portion l5 of cam element I4 and positively rotates the cam element in a clockwise direction, so as to partially open the choke valve. This movement of the cam also releases extension I from finger 20 and permits spring 29 to rotate plate element 3 and the throttle valve in the throttle opening direction until plate extension 1 engages finger 33 on crank 25. Such opening of both the choke and the throttle valves before the choke control thermostat reaches normal operating temperature permits "unloading the engine intake system in a well known man ner.

The accelerating pump 45 being operated by the opening movement of the throttle valve, discharges a very small portion of its capacity during the positioning of the throttle valve as shown in Fig. 1, and is inoperative during the movement of crank 25 from the position shown in Fig. 1 to the position shown in Fig. 2. When the throttle valve 4 is allowed to open for unloading the resistance set up in the pump acts as a dash pot to The added resistance by the spring 29, to the clockwise movement of crank 25, from the position shown in Fig. 1, is sufiicient to indicate to the operator that the throttle valve has been correctly positioned for starting a cold engine. After the engine has started and crank 25 rotated counterclockwise, ball will be released and picked up by the suction applied to the upper face thereof through a passage (not shown) opening into the carburetor barrel posterior to the throttle.

The invention may be modified in various respects as will occur to those skilled in the art and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a carburetor, choke and throttle valves, choke operating mechanism including a thermostatic device for yieldingly closing said choke valve for cold starting, means to open said throttle valve including a member yieldingly connected thereto, said member when moved substantially in the throttle opening direction engaging said choke operating mechanism to open said choke valve, and means actuated by closing of said choke valve for positively limiting the opening movement of said throttle valve by said member to a predetermined starting position.

2. In a carburetor, choke and throttle valves, means for closing said choke valve, a manual control having a. spring connection .to said throttle, and a device movable, responsive to closing of said choke valve, to a position for positively limiting the movement of said throttle valve, by said manual means, in throttle opening direction, said manual means being constructed and arranged, when moved farther in said direction, to displace said device from said throttle limiting position and also to open said choke, whereupon said spring opens said throttle valve.

3. In a carburetor, choke and throttle valves, an accelerating pump, means for closing said choke valve, a throttle actuating crank having resilient operating connections to said throttle and said pump, and means actuated by movement of said choke valve to choking position for positively limitingthe opening movement of said throttle and discharge from said pump said crank being constructed and arranged, when moved substantially beyond the position of throttle limitation, to displace said limiting means from its throttle limiting position and thereby permit further opening of said throttle valve, and discharge of said pump.

4. A carburetor as specified in claim 3 in which said pump functions as a dash pot to retard the opening of said throttle valve when said throttle and pump limiting means is moved from its limiting position by said crank.

5. In a carburetor, choke and throttle valves,

5 tion for positively limiting the opening movement of said throttle, said arm being constructed and arranged, when moved substantially beyond the position of throttle limitation, to displace said limiting means from throttle limiting position and 10 thereby permit further opening of said throttle valve under the influence of said resilient operating connection.

IRVEN E. COFFEY. 

